Automatic Transmission Shift Control via Torque Distribution
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Solution Overview
Problem
Existing automatic transmission control systems face challenges in smoothly and stably controlling the engagement and disengagement of frictional engagement elements during gear shifts, particularly in down-shifting, due to complex relationships between engagement and disengagement side elements, leading to potential shocks and inefficiencies.
Innovation Solution
A control apparatus and method that sets target difference revolution speeds and calculates individual torque capacities for first and second frictional engagement elements, allowing for separate control of their engagement conditions to manage torque distribution and rotation speed differences, thereby facilitating smoother and more stable down-shifts without shocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional oil pressure control methods are used for frictional engagement elements, then the control system is simple, but shift smoothness and shock reduction are insufficient
Solution Approach 1:
The control system is segmented into separate control paths for engagement-side and disengagement-side frictional engagement elements. Each side has independent control parameters including target oil pressures, sweep-up gradients, and feedback control characteristics. This segmentation allows optimized control for each element without requiring complex coordinated control, improving shift smoothness while maintaining manageable system complexity.
Solution Approach 2:
The system performs preliminary actions by pre-calculating target oil pressures and sweep-up gradients before the actual engagement or disengagement occurs. The engagement-side element has its target pressure and gradient prepared in advance, and similarly for the disengagement-side element. This preliminary preparation enables smooth transition without shocks while keeping the control logic systematic and manageable.
2Stability of the object's composition
If separate control of engagement and disengagement elements is implemented, then shift stability improves, but control calculation complexity increases
Solution Approach 1:
Different control qualities are applied locally to engagement-side and disengagement-side elements. The engagement-side element uses a control strategy with specific target pressure and sweep-up gradient characteristics, while the disengagement-side element uses different parameters optimized for its function. This local differentiation improves shift stability by addressing each element's specific requirements without requiring overly complex global coordination.
Solution Approach 2:
The system changes control parameters specifically for each frictional engagement element based on its role. Engagement-side elements have parameters optimized for smooth engagement, while disengagement-side elements have parameters optimized for controlled disengagement. These parameter changes are implemented independently for each element, improving shift stability while maintaining clear and separate control logic that doesn't excessively increase calculation complexity.
3Manufacturing precision
If torque distribution is managed separately for each element, then shift precision improves, but control system complexity increases
Solution Approach 1:
Torque distribution control is segmented into independent control loops for engagement-side and disengagement-side elements. Each element's torque capacity is controlled separately through its own oil pressure management, allowing precise torque distribution without requiring complex inter-element coordination. This segmentation achieves high shift precision while keeping each control loop relatively simple and manageable.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables easier and more stable shift control by managing torque distribution and rotation speed differences between engagement and disengagement elements, improving shift smoothness and reducing the risk of shocks across various automatic transmission types.
Implementation Method 1
a control apparatus and controlling method for an automatic transmission that appropriately changes a rotation input from an engine and outputs it by engaging certain frictional engagement elements from a plurality of the frictional engagement elements
Data Source
AI summary
A control apparatus of an automatic transmission having first and second frictional engagement elements that achieve higher and lower speed gear stages respectively, includes a target value determination section setting a rotation speed difference between input and output sides of the frictional engagement element, a total torque capacity calculation section calculating a total torque capacity, a distribution ratio determination section setting a distribution ratio of the total torque capacity to the first and second frictional engagement elements, an individual torque capacity calculation section calculating individual torque capacities respectively required of the first and second frictional engagement elements, and an engagement control section controlling engagement conditions of the first and second frictional engagement elements in accordance with the individual torque capacity. The automatic transmission realizes a down-shift by changeover between first and second frictional engagement elements based on the individual torque capacity during a vehicle power-off travel.